Guest article: Hydrogen Filling Stations for Buses - Lots of New Developments in the West!

A guest article by Claus Bünnagel, Editor-in-Chief of busplaner

The Rhein-Erft district decided back in 2019 to switch to locally emission-free hydrogen buses in the future. By the end of June 2025, 26 Solaris Urbino 12 hydrogen buses, each with a 70 kW Ballard fuel cell, had been procured in a first tranche from REVG Rhein-Erft-Verkehrsgesellschaft mbH. The investment was subsidized by the Federal Ministry of Transport with €7.48 million before the end of 2024, when subsidies for electric and hydrogen buses were discontinued. At approximately €288,000 per vehicle, this roughly corresponds to the additional cost of fuel cell buses compared to their diesel counterparts. REVG Managing Director Walter Reinarz estimates this at around €300,000 per unit. There are also plans to purchase seven H2 articulated buses. Together, they will gradually replace diesel vehicles with expiring leasing contracts.

With 500 bar storage

Of course, an adequate filling station infrastructure is also required for the growing hydrogen bus fleet. A filling station operated by the neighboring Spedition Freund transport company was therefore built at the REVG depot on Röntgenstraße in Kerpen, on the southwestern outskirts of Cologne, by October 2024. This facility has a 900-bar high-pressure storage tank with a cooling system (for temperatures down to −40 °C), a 500-bar low-pressure storage tank, and a compressor costing €1.5 million alone. Although the high-pressure storage tank can only supply 15 kg of H₂ fuel, it can also supply the REVG's car fleet with 700 bar hydrogen. In theory, it could also be used to refuel buses. However, these are more likely to be supplied by a low-pressure storage tank, which can hold 50 kg.

However, in order to be able to refuel a bus every 20 minutes in the future, mainly in the evening after the buses return from their routes, the delivery of hydrogen by trailer by Messer SE from Krefeld must be expanded. The company is the world's largest privately owned specialist for industrial, medical, and specialty gases.

So far, two trailers per day deliver 200-bar compressed hydrogen, which must be brought to 350 bar on site. One trailer holds 300 kg, which is enough to supply 13 buses, or approximately 23 kg per bus. With a consumption of 7 to 8 kg/100 km, this is sufficient for 290 to 330 km. This roughly corresponds to the scope of many daily routes at REVG. The five type 4 tanks on the roof of the Solaris fuel cell buses have a volume of 1,560 liters and can hold up to 37.5 kg of hydrogen. This means that even the 400 km of the longest daily routes at the Rhineland transport company can be covered.

In the future, 380-bar trailers will even be used. They can each transport one ton of hydrogen. In addition, the fuel for the buses no longer needs to be compressed. To supply the future H2 trucks of the Freund freight forwarding company, three such 40-ton trailer trucks would be in use: one would be filling up for four to five hours, one would be on the road, and one would be at the REVG depot at the filling station.

Until now, the Messer Group has been supplying hydrogen from its production plant on the Rain Carbon company premises in Castrop-Rauxel. However, at the beginning of July 2025, the ground-breaking ceremony for an H2 plant with a 10 MW electrolyzer took place at Brainergy Park Jülich. The plant is scheduled to go into operation in November. The electrolyzer technology is supplied by the NEA Group from Übach-Palenberg. Messer SE, in turn, is responsible for the storage and distribution of the hydrogen generated from photovoltaic electricity.

REVG currently expects hydrogen prices to range between the standard 14 and 18 euros per kilogram. However, if large electrolysers with a capacity of 25 MW can be used in the future, prices per kilo of 9 to 10 euros are expected in Frechen, plus distribution and delivery.

Europe's largest hydrogen filling station

Not far down the Rhine from Cologne, H2 Mobility officially opened Europe's largest hydrogen filling station in Düsseldorf at the end of May 2025. It has been in operation since the beginning of August. It was funded with €4.3 million by the Federal Ministry of Transport's National Innovation Program for Hydrogen and Fuel Cell Technology (NIP, Phase II, 2016–2026). The facility cost a total of around €7 to €7.5 million.

Its location on Höherweg in the east of the city is no coincidence, as from 2026, hydrogen will be supplied via a 2 MW PEM electrolyzer operated by Stadtwerke Düsseldorf. The electrolyzer's electricity requirements will be covered by the neighboring waste incineration plant. Fifty percent of the electricity is to come from renewable raw materials and thus be certified as green electricity. Air Liquide currently still supplies the hydrogen via a 380-bar trailer from its electrolyzer in Oberhausen.

The most important customer of the public H2 Mobility filling station is Düsseldorf's Rheinbahn with its nearby Lierenfeld depot. It currently operates 20 Solaris Urbino 12 hydrogen buses on line 732 and plans to increase its H2 fleet to around 30 units in the short to medium term. The facility has three dispensers with a total of six fuel pumps, all of which can be used simultaneously. Here, hydrogen can be refueled at 350 bar (for buses and trucks), 700 bar (for cars), and 500 bar, which must be cooled to −20 °C. The latter is available in a test and pilot phase at the price of 350 bar hydrogen. Currently, prices at the Düsseldorf filling station range from €13.55/kg (350 and 500 bar) to €15 (700 bar). However, H2 Mobility admits that these prices are close to the purchase price. The entire facility is designed to supply customers with 2 to 5 tons of hydrogen per day. The 30 Rheinbahn fuel cell buses alone already account for a daily purchase volume of around 750 kilograms

Two refueling concepts for one company

The refueling concept of Regionalverkehr Köln GmbH (RVK) and Stadtwerke Hürth, which are considered pioneers in the field of hydrogen mobility in public transport, is designed quite differently. RVK is pursuing two different concepts. The two new H2 filling stations in Mechernich and in the Moitzfeld district of Bergisch Gladbach are being built and operated by the transport company itself in its own depots. They are equipped with 2 MW electrolysers to use electricity from wind and PV systems for their own hydrogen production.

The situation is different for the filling stations in Meckenheim and Hürth, where significantly more vehicles will have to be supplied in the future than in Moitzfeld and Mechernich. For this purpose, land was sold by the two cities to RVK and Stadtwerke Hürth on the condition that other users – from municipal utilities to freight forwarders and bus companies to private individuals with cars – would also have access to the hydrogen filling stations. Following the tendering process, Air Products, as the lessee of the respective plots of land, was responsible for the entire process – from the approval procedures and construction to the future operation and supply of hydrogen to the publicly accessible filling stations. This is a turnkey and elegant solution for RVK and Stadtwerke Hürth.

The design of the two new filling stations in Meckenheim and Hürth differs fundamentally from the previous RVK depot model. The hydrogen is supplied by Air Products from its own sources and via new 640-bar trailers. This supply solution eliminates the need to compress the hydrogen to 350 bar, as the hydrogen flows directly from the trailer into the fuel dispenser via overflow.